STIHL MS461 BGD

[John7478]

I will definitely agree with that.
Every time I start it for the first time of the day it just bellos smoke and yeah runs fat as once she's warmed up totally different story opposite end of the scale

Where do you get your Mobil 1 2t from?

 

[deye223]

Where do you buy your Mobil 1 2t from?

Where do you get your Mobil 1 2t from?

I bought a box 4x4lt last year from my local Mobil servo and I did not see any last time in there so I think unfortunately I got the last of it Mobil do have a full synthetic oil at the moment but I don't know if it's as good I just know it's not the same.

 

[deye223]

This is their new stuff we can get heaps of it here.

https://www.mobil.com.au/en-au/lubricants/our-products/products/mobil-1-racing-2t

 

[Bigmac]

I really like the bgd on these, really woke mine up, has a lot more grunt. Mine jumped from 165 to 175psi. Not a massive jump but enough, that saw didn’t need the bolts shaved but my other 461 did, so always check!!! The second one I lowered the intake a little and lifted the exhaust a touch, I like them both, the saw with the bgd and muffler mod has a Torquey feel and can run a longer bar better, and the other has a better upper rpm power, both are stronger than stock. I didn’t do a timing advance on the bgd saw because it will snap back on the recoil as is, the other 461 has 170 psi and starts great even with timing advance, it’s odd 5 psi would make that kind of difference but it did in this case. I would not hesitate to do it!

plus it’s just a bgd, so all you have to do is put that gasket back in if you done feel it’s a gain. It’s super easy, and you probably won’t put the gasket back!

 

[Bigmac]

A member on AS wrote this, I think he knows a lot about 2 strokes:

I want to put to bed the myth of high compression in chainsaws,having worked on 2 stroke racing engines since the 70's I want to lay some straight facts down. High compression was first made popular during the 60's with big v-8 racing engines(4-stroke) and compression ratios went up to 13-1 or more. But the best 2-stroke racing engines actually reduced the compression ratio from the stock engines. Why,because the more the compression ratio the more horsepower it takes from the engine to crank the engine against that high compression,at some rpm the HP taken to crank that high compression takes more HP than it makes,and then the engine starts to lose HP. Thats why a factory motor making 60 HP at 8.5-1 compression,makes 100HP at 7.5-1 comp. ratio.
Now higher compression does make more power at low and mid range power for sure,but not many saws run in that range. so if you want more low end or mid range power compression is good,but if you need high rpm race power high compression will simply cost you Hp. As my instructor told me in 1975 "high compression fights high rpms",he was right.
So more more compression can help you,but not at high rpm's.
When you yank the cyl. gasket out of a saw you do gain some compression,BUT you also lower the exhaust and transfer ports down,reducing their duration,and reducing higher rpm power. I would much prefer to raise ports than compression for power,much more can be gained.
In many engines I would much prefer to raise the exhaust port and lose compression,I know I will make much more top end power.
Removing the cyl. gasket and lowering the transfer ports is really bad,you reduce their duration and reduce their open time from tens of thousanths of a second to even less!

what do u guys think about that?
Before I read this, I want to make a bgd but now I’m not sure if it is worth the time.

I believe there was at least one dyno test that was done with a bgd only and it gained 1hp. I think there are very few stock saws that would not gain from a little more compression. I don’t have vast experience like many of the builders here, but 175-190 psi seems to be the sweet spot. I have had a few 066-660’s and most land at 150-150psi, some have 170-175 psi stock, those saw run much better imho, I have played a little with machine work on one of mine and it was right at 200psi and it still revs fine, it’s not like it hit a compression wall. In the atv world I have done more tuning work, and have had more chances to test squish and compression along with different dome designs. I have tested domes at 1cc intervals, on my banshee, I pushed it to the point it would rev at all, it literally hit a wall, one cc less and it would rev 3k more rpm, one cc less than that and it would rev even farther, but really hurt low end power and power over all, it really likes 175-180psi, on the other hand my single cylinder Honda loves compression, it doesn’t rev as far as the banshee, but it still sees gains above 220psi. I guess there are a lot of factors, but I don’t feel a bgd will hurt the 461!